This invention relates to printing systems that imprint documents with a barcode and utilize downstream processes to track that the current number of pages in the document are present, and more particularly to such printing and tracking systems which utilize invisible ink for the barcoding.
Electrophotographic printing systems are known that print black barcodes during the printing of documents, and use barcode scanners in downstream processing to verify information and to check that the proper number of pages are present in the document. These systems are typically used for the printing and tracking of insurance documents, checks, manuals and other print-on-demand documents. Some customers find objectionable the appearance of visible barcodes on their documents.
Conventional industrial inkjet barcode printers typically use printheads having a dot per inch spacing of 150 dots per inch (dpi) to 240 dpi, and have traditionally been continuous inkjet printers. These low dpi printheads produce drops that are large and consequently produce spot sizes on the print media that are relatively large. Ink formulation is also important in determining the spot size. It is this spot size that fundamentally determines the minimum barcode sizes that a printhead can print.
Accordingly, it would represent an advance in the art to provide a technique for imprinting barcodes on documents and subsequently scanning the documents for verification purposes which did not rely on visible barcode features.
It would further represent an advance in the art to provide a technique for producing smaller, denser barcodes on documents, and thereby increase the amount of data to be stored in a given area, increase the edge acuity of the printed barcodes and resulting scan reliability of the system.
A document printing and verification system is described. The system includes a printing apparatus for printing an image on a print medium, and an inkjet printer apparatus for printing an invisible identification pattern on the print medium which is invisible to the unaided eye under natural illumination. A scanner apparatus is positioned for producing an image of the identification image for verification use. The scanner apparatus includes a light source for illuminating an imaging zone with light including nonvisible energy components and a camera sensitive to nonvisible light from the print medium to form an image of the nonvisible identification image.
In accordance with another aspect of the invention, the inkjet printhead is a high resolution printhead adapted to provide inkjet barcode printing resolution at least as high as 600 dots per inch. This improves the edge acuity of the barcodes, and permits very high density barcode information to be imprinted on the document page.
In accordance with another aspect, the ink used to form the invisible barcode includes a UV dye and an FR/IR dye. The UV dye when illuminated with UV light provides an image of the barcode which is visible to the unaided eye, providing a visual check on the system operability. The FR/IR dye is imaged using an FR/IR camera to capture electronically an image of the barcode. The captured image is then used by the controller for verification purposes.
Yet another aspect of the invention includes backlighting the document page with FR/IR energy, and capturing an image of the barcode with an FR/IR sensitive camera. The FR/IR energy penetrates the page sufficiently to excite the FR/IR dye in the barcode ink.
Another aspect of the invention is a method for document printing and verification, comprising the following steps:
printing a page of a document;
printing an identification pattern on the document page using an inkjet printer, the pattern printed with ink which is invisible to the unaided eye under natural light illumination;
illuminating the document page with light energy including energy components in a non-visible band;
electronically capturing an image of the identification pattern at the imaging zone; and
performing a verification procedure using the electronically captured image.